docs: def _symmetrize_correlograms(correlograms):
      """Return the symmetrized version of the CCG arrays."""
  
      n_clusters, _, n_bins = correlograms.shape
      assert n_clusters == _
  
      # We symmetrize c[i, j, 0].
      # This is necessary because the algorithm in correlograms()
      # is sensitive to the order of identical spikes.
      correlograms[..., 0] = np.maximum(correlograms[..., 0],
                                        correlograms[..., 0].T)
  
      sym = correlograms[..., 1:][..., ::-1]
      sym = np.transpose(sym, (1, 0, 2))
  
      return np.dstack((sym, correlograms))